cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A318734 a(n) = Sum_{k=1..n} (-1)^(k + 1) * d(2*k - 1), where d(k) is the number of divisors of k (A000005).

Table of values

n a(n)
1 1
2 -1
3 1
4 -1
5 2
6 0
7 2
8 -2
9 0
10 -2
11 2
12 0
13 3
14 -1
15 1
16 -1
17 3
18 -1
19 1
20 -3
21 -1
22 -3
23 3
24 1
25 4
26 0
27 2
28 -2
29 2
30 0
31 2
32 -4
33 0
34 -2
35 2
36 0
37 2
38 -4
39 0
40 -2
41 3
42 1
43 5
44 1
45 3
46 -1
47 3
48 -1
49 1
50 -5
51 -3
52 -5
53 3
54 1
55 3
56 -1
57 1
58 -3
59 3
60 -1
61 2
62 -2
63 2
64 0
65 4
66 2
67 6
68 -2
69 0
70 -2
71 2
72 -2

List of values

[1, -1, 1, -1, 2, 0, 2, -2, 0, -2, 2, 0, 3, -1, 1, -1, 3, -1, 1, -3, -1, -3, 3, 1, 4, 0, 2, -2, 2, 0, 2, -4, 0, -2, 2, 0, 2, -4, 0, -2, 3, 1, 5, 1, 3, -1, 3, -1, 1, -5, -3, -5, 3, 1, 3, -1, 1, -3, 3, -1, 2, -2, 2, 0, 4, 2, 6, -2, 0, -2, 2, -2]